Explosives are used widely throughout the world for a variety of applications including oilfield and mining. One application of explosives used commonly in the oil industry is the use of perforating guns, which are also termed wireline guns. The perforating guns are tubular assemblies that contain a series of explosive shaped charges. When detonated the shaped charges create a molten high-pressure jet that creates a perforation into the hydrocarbon bearing formation. The hydrocarbons can then flow into the wellbore for production of the well.
These perforating guns are commonly loaded (with shaped explosive charges) in shops or specially designated areas for safety concerns. These requirements are set by the government agencies in charge of explosive regulation. These requirements include the use of explosive magazines for storage of explosive charges and detonators and the use of shock absorbing mats in the loading areas. Security is often an issue since these areas are often open to the remainder of the shop. However, it is desirable that the areas be secured to ensure only trained personnel have access to explosives.
However, recently, it has become apparent that present loading facilities sometimes do not adequately address the risk of injury to personnel and equipment should an accidental detonation occur. In particular, the shrapnel generated by an accidental detonation perforating gun detonation can pass into adjacent open or separated work areas injuring personnel who are not at all involved in the handling of explosives or in the industry of perforating guns in general. To mitigate this risk, it has been proposed that any bay for handling perforating gun explosives be isolated to provide, what is termed a “safe quantity distance” between the loading bay and adjacent unrelated shops and people. For perforating gun-sized explosive handling, of for example, less than 20 kg explosives, the safe quantity distance can be for example 270m. As will be appreciated, this has complicated perforating gun loading operations as it is often very difficult to provide safe quantity distance about the entire bay.
Another problem that must be addressed is relating to storage of the explosives. Explosives must be maintained in secured storage areas when not being handled to prevent access by unauthorized personnel. This often requires that the explosive be transported into and out of magazines on a regular basis, which increases the chances of accidents.
Considerations need to be made for mitigating the risks of perforating gun explosives handling.